Protection against ultra-violet (UV) radiation, such as from the sun, has become an important issue in the preparation of personal, household and automotive products in recent years. Depletion of atmospheric ozone has led to an increase in the amount of atmospheric UV radiation, and concurrently has resulted in the need to filter out such harmful rays.
Silicone polishes are commonly used to improve the appearance of, as well as to protect, household products, luggage, marine and automobile vinyl and the like. While silicone polishes are generally considered excellent by those skilled in the art, they suffer from the shortcoming that when they are prepared by conventional mechanical methods, the ultraviolet light absorbing agents contained therein are considered to be fugitive materials, from the standpoint of various external conditions such as weathering, abrasion, heating and the like.
Silicones with fugitive UV agents can also be utilized in emulsion form for use as a treating agent for fabrics, upholstery, carpeting, draperies and the like. Treatment with such silicone emulsions imparts water and dirt repellency to the fabric as well as UV resistance.
It is further known that fugitive UV agents can be added to silicones for use in cosmetic applications such as make up, sun tanning lotions and hair products. Lamb et al., U.S. Pat. No. 5,049,377 teaches the use of UV absorber additives in a hair care composition comprising hydrophobic cationic emulsions of highly branched and/or crosslinked polydimethylsiloxane.
In each of the foregoing applications, while the protection against UV radiation lasts for a finite period of time, due to weathering, abrasion and heating etc. the protection is lost much sooner than desired. Accordingly, attempts have been made in the art to provide a UV absorbent silicone polymer which has improved resistance to weathering.
Forrestier et al., U.S. Pat. No. 5,089,250, teach a benzotriazole-containing diorganopolysiloxane cosmetic, prepared by a hydrosilation process comprising (i) preparing a benzotriazole derivative by reacting an alkenyl halide with a benzotriazole compound, and then (ii) reacting the benzotriazole derivative with a silicone hydride.
Hill et al., U.S. Pat. No. 4,554,369, teach the preparation of organosilicon compounds which are useful as sunscreens and which are prepared by reacting an epoxy containing siloxane with the appropriate acid or acid chloride.
Special mention is made of Thimineur et al., U.S. Pat. No. 4,696,969 which discloses emulsion polymerized silicone emulsions having siloxane bonded UV absorbers. The patentees teach dispersing the siloxane in water with an emulsifier, adding the UV agent during emulsion polymerization of the siloxane to chemically bond the UV agent to the resulting emulsion polymerized polydiorganosiloxane.
It has now been discovered that a novel UV containing curable silanol-terminated siloxane polymer can be produced, and that such compounds have excellent retention of UV resistant properties under conditions of weathering.